NEUROGLIA AND SENSE ORGANS 553 



can be used in the proportions of 4, 5, 6, 7, 8, 9, 10 and 11 parts 

 of (A) to 16, 15, 14, 13, 12, 11, 10 and 9 parts of (13), and 1, 2, 4, 

 5, 6, 7, 8 and 12 parts of (C). After staining, the tissue is rinsed 

 in running water and frozen sections are cut at 35 /x. 



BoLSi {Riv. d. Pat. Nen. e Ment, xxxii, 1927, pp. 51 and 898) 

 fixes tissues in 5 c.c. each of pyridine and acetone ; formol, 15 c.c. ; 

 ammonium bromide, 3 grm. ; distilled water, 75 c.c, for six days 

 to six months. Frozen sections are cut at 15 /x and well washed in 

 distilled water before being stained in an ammoniacal silver 

 solution prepared by adding ammonia to 10 c.c. of 2 per cent, 

 silver nitrate until the resultant precipitate is dissolved and 

 then adding 20 c.c. of glycerin. The sections are reduced in 

 20 per cent, formalin. This method stains neuroglia and microglia. 

 To stain microglia only, frozen sections are passed from distilled 

 water into glycerin, 40 c.c. ; ammonia, 100 drops ; distilled 

 water, 160 c.c. ; being constantly moved about in this solution 

 for five minutes before being stained in 2 per cent, silver nitrate 

 for one minute and reduced in 1 to 2 per cent, formalin for five 

 minutes. 



DuBRAUszKY {Zeitschr. f. d. ges. Neurol^ u. Psychiat., cxxvi. 

 1930, p. 230) fixes small pieces of brain for forty-eight hours in 

 formalin, 6 c.c. ; sodium bicarbonate, 6 grm. ; 15 to 20 per cent, 

 ammonia, 16 drops ; distilled water, 100 c.c. Frozen sections are 

 washed first in weak ammonia water and then in distilled water 

 and immersed in a silver bath prepared by adding 1 drop of 

 strong ammonia to 1 c.c. of 20 per cent, silver nitrate, diluting 

 with distilled water to 15 c.c, and filtering the solution before use. 

 The time of impregnation is about fifteen seconds. The sections 

 are reduced in | per cent, formalin to which 1 drop of silver nitrate 

 for each 20 c.c. of formalin is added. 



VizioLi {Riv. d. Neurol., v, 1932, p. 165) places frozen sections 

 of formalin fixed material in Dubrauszky's fixative (see above), 

 in which the sodium bicarbonate is replaced by sodium carbonate. 

 He then transfers them to Bolsi's ammoniacal glycerin solution 

 (see above) and after a rapid wash, to Bolsi's ammoniacal silver 

 nitrate. Very dilute formalin (30 to 40 parts in 1000 c.c. of water) 

 is used for reduction, which takes about one to two hours. 



1097. Other Methods for Microglia. Penfield {Am. Journ. 

 Path., iv, 1928, p. 153) places frozen sections of formalin fixed 

 material in weak ammonia water overnight and then transfers 

 them directly to 5 per cent, hydrobromic acid for one hour at 

 37° C. After being washed in three changes of distilled water, 

 sections are put into 5 per cent, sodium carbonate for one to six 

 hours, and are subsequently stained in Hortcga's silver carbonate 

 solution diluted to 75 c.c, until they turn a light brown colour. 



Kanzler {Zeitschr. f. d. ges. Neurol, u. Psychiat., cxxii, 1929, 

 p. 416) heats frozen sections of formalin fixed tissues till vapour 



